Step forward Warren Buffett, the billionaire founder of Berkshire Hathaway, who has admitted to an investment that has lost him nearly $900m (£537m) – after he failed to consult his long-time business partner.

In his annual letter to Berkshire Hathaway shareholders published at the weekend, Mr Buffett said he wished he had “never heard” of Energy Future Holdings (EHF), a company founded seven years ago to buy Texas electricity utilities. It now appears to face certain bankruptcy.

“Unless natural gas prices soar, EHF will almost certainly file for bankruptcy in 2014. Last year, we sold our holdings for $259m. While owning the bonds, we received $837m in cash interest. Overall, therefore, we suffered a pre-tax loss of $873m. Next time I’ll call Charlie,” wrote Mr Buffett.

His admission came in a year when Berkshire Hathaway failed to outperform the S&P 500 index, only the tenth time this has happened since Mr Buffett founded the business 49 years ago.

Taken over their life, the value of Berkshire shares have easily outperformed the stock market, with the book value of each Berkshire increasing by 693,518pc since 1965, compared with 9,841pc for the S&P. Mr Buffett added that Berkshire’s intrinsic value “far exceeds” the book value and said the difference between the two measures had “widened considerably in recent years”.

He added: “Charlie Munger, Berkshire’s vice chairman and my partner, and I believe both Berkshire’s book value and intrinsic value will outperform the S&P in years when the market is down or moderately up. We expect to fall short, though, in years when the market is strong – as we did in 2013. We have underperformed in 10 of our 49 years, with all but one of our shortfalls occurring when the S&P gain exceeded 15pc.”

With such a long track record of success, Mr Buffett’s annual letters are closely followed around the world for his views on the market.